Owing to advantages such as high working efficiency and capability of securing a good working environment, an injection molding machine has been widely applied to molding of Mg and Mg alloys. It is necessary for a cylinder component in the injection molding machine to have excellent high-temperature properties since it comes into contact with molten Mg alloys. Therefore, for the cylinder component, it has been proposed to use Ni-base heat-resistant alloys.
However, in general, since the Ni-based heat resistant alloys are severely corroded when they come into contact with molten Mg alloys, it is necessary to perform lining on the inner surface of the cylinder with a material excellent in corrosion resistance. It is said that a Co-base alloy is suitable as the lining material and, hitherto, some technologies for improving the corrosion resistance by lining a cylinder component for a light-metal injection molding machine with a Co-base alloy have been reported (PTLs 1 to 4).
For example, PTLs 1 and 2 disclose technologies for imparting the corrosion resistance by joining a coating layer such as a Co-based alloy to the inner surface of an Ni-base superalloy cylinder for a light-alloy injection molding machine by HIP method. Moreover, PTL 3 discloses a technology of forming a coating layer such as a Co-base alloy on the inner surface of a cylinder base material for a light-metal injection molding machine, which is composed of an austenite-based steel material, to improve the corrosion resistance. PTL 4 discloses a technology of constituting wide variety of high-temperature components such as a cylinder, a screw, and a screw head of a low-melting-point metal injection molding machine by an Ni-base heat-resistant alloy and further coating the components with a Co-base heat-resistant alloy.